L4S stands for “Low Latency, Low Loss, and Scalable throughput”.
The objective is to minimize the idle waiting time of your packets in queues, aiming to reduce the necessity for queuing as much as possible.
So, a technology intended to reduce queue delay problems, ensuring low latency to Internet Protocol flows with a high throughput performance.
To reach this goal, it relies on Explicit Congestion Notification (ECN), a mechanism that marks packets to signal congestion in the network avoiding packets to be dropped.
The congestion signals are managed at the sender and receiver sides thanks to scalable congestion control algorithms.
L4S can also be used in a combination with a Delay Based Scheduler (DBS), to minimize packet loss.
But, speaking in a more easy to understand way: 
It’s like a new revolution in Internet speed, which could surpass several limits, very different from what we have now.
We live in an era of transformation, and this revolution may have a name: L4S technology
In short, it is the promise of a faster, more stable and efficient internet, in an interconnected world, where the Internet is vital for countless areas, from entertainment to education and research, L4S emerges as the promise of significant change.
This technology has the “power” to eliminate the everyday “headaches” we face on the Internet, offering a virtually latency-free connection and an agile data connection.
Imagine pages loading practically instantly, video calls without crashes, automatic video playback and surprising download and upload speeds.
Even on a very high-speed connection, low latency can lead to problems loading pages, videos buffering during playback, video calls failing, etc.
One of the main causes of this problem is the so-called “buffer bloat”, which occurs when network devices have to deal with a large amount of data and need to queue these packets to be sent (which can add a significant amount of latency). .
But how does this technological marvel work?
L4S acts as an invisible guide to the data, identifying congestion, and resolving problems instantly.
Adds an indicator to data packets to let you know if they experience congestion during their journey through the network.
This allows devices to make immediate adjustments to avoid congestion and ensure continuous data flow – therefore reducing latency.
In simpler terms, it’s as if L4S were an Intelligent Traffic Assistant on the Internet, avoiding traffic jams and keeping data flow fast and efficient.
Imagine always having the fastest path available, adapting instantly to avoid delays in delivering information.
The result of L4S is a simplification of the online experience, providing smooth and efficient navigation - a true revolution.
Of course, this revolution is not simple, and has complex technology behind it.
Many companies such as Apple, Google, Nvidia, Comcast are already diving into this technological advancement, recognizing the transformative potential of L4S.
You can be sure, you will hear about it soon. (Of course, for those who didn’t know yet)
And now you are ready (technical background) to read what The Verge says here (nice article with technical solution): Apple, Google, and Comcast’s plans for L4S could fix internet lag - The Verge